The invention relates to an aluminum die-cast part, in particular a structural component for a motor vehicle, in which, for protection against sudden breaking loads, at least one tension element made of a material which can undergo ductile deformation and which has a coefficient of thermal expansion different to the cast part is adhesively bonded in a load-resistant manner to that side of the cast part opposite the applied load.
DE 10 2011 076 426 A1 discloses an aluminum die-cast part of this type in the form of a spring support for a motor vehicle. The risk of the cast part breaking in the event of a crash is markedly reduced by the fact that, on that side of the cast part opposite the applied load, one or more tension strips made of a material which has high tensile strength and which can at the same time undergo ductile deformation are attached continuously over the entire length of the tensile strip by use of a viscoplastic adhesive bond so as to transfer loads and in particular shear loads. In this manner, the impact loads acting on the cast part are taken up by the tension strips on the side opposite the applied load such that, in the event of a crash, the cast part can deform largely without breaking. However, under operating conditions and especially under the effect of high temperature differences during curing of the adhesive system, the different coefficients of thermal expansion—inherent to the materials—lead to unequal changes in length between the cast part and the tension strips, which can impair the break-proof deformability of the crash-proof aluminum die-cast part.
The invention has the object of designing an aluminum die-cast part of the above-mentioned type such that the break-proof deformability of the cast part is retained unaltered even after relatively large temperature variations as can occur under extreme operating conditions or during heat curing of the adhesive system.
This and other objects are achieved according to the invention by providing an aluminum die-cast part in accordance with embodiments of the invention.
According to the invention, the tension element and the cast part are divided into individual partial sections which are each connected to one another in a shear-resistant manner at mutually separated fixing points. The partial sections counteract the respective differences in thermal expansion between the tension element and the cast part over a wide temperature range. Thus, the resulting shear stresses in the adhesive layer are kept within the permitted limit values. In this manner, thermally-induced delamination phenomena or crack formation within the adhesive bond are effectively prevented with low manufacturing cost, such that the cast part retains full functionality even after the effect of relatively large temperature variations of up to 200° C., for example during heat curing of the adhesive.
In a particularly preferred configuration of the invention, for reasons of simplified production, the aluminum cast part and the tension element are welded to one another at the mutual connection points or are secured in a form-fitting manner in the shear direction.
Extensive testing has shown multiphase steel, in particular of the type HC 600, to be a particularly advantageous material for the tension element, wherein this steel is expediently combined with a cast part made of an AlSi alloy.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.